This invention refers to a self-closing cap for the filler necks of liquid containers such as barrels, canisters, tanks and the like, as well as fuel tanks of motor vehicles, consisting of a closure ring with a seal, said ring being attachable to the filler neck, and of a closure flap swivel-mounted on said closure ring and provided with a seal, said flap being opened during the filling of the container by the nozzle of a hose or similar arrangement inserted into the filler neck and automatically closing under the influence of a spring upon withdrawal of the nozzle from the filler neck.
A wide variety of filler neck caps of the type in question has become known. For the most part, they are complex in design and have complicated forms, resulting in relatively high production costs for the cap.